1. Field of the Invention
The present invention relates to a chain conveyor system for loading and conveying articles to be conveyed (referred to simply as articles hereinafter) and more specifically to a chain conveyor system for conveying metallic magnetic articles by securely attracting and retaining the articles even on such a conveyor line inclined upward or downward or on a slippery wet conveyor line.
2. Related Art
Conventionally, there has been known a chain conveyor system for conveying magnetically attractive articles so as not fall by using a magnet-backed chain having a large number of attractive magnet units disposed at certain intervals on an outer circumferential side of a chain base. In each attractive magnet unit, a surface of permanent magnet fixed to a thin ferromagnetic yoke is coated by epoxy resin and the like as disclosed in Japanese Patent Application Laid-open No. Hei.9-27511 (Paragraph 8, FIG. 8) for example.
However, because the large number of attractive magnet units is disposed on the outer circumferential side of the chain base in the prior art chain conveyor system using the magnet-backed chain, there have been problems that not only do the attractive magnet units come in contact directly with the metallic magnetic articles, thus displacing or damaging the permanent magnets, but also the chain conveyor system generates noise due to the contact or impact by the articles on the magnet units.
Still more, because the attractive magnet units continue to be directly in contact with the metallic magnetic articles and to exhibit their strong attractive force even in a terminal discharge area of the conveying run of the prior art chain conveyor system, it often has been difficult to release or separate the articles, posing a serious hindrance in transferring the articles, due to the strong attractive force of the attractive magnet units in transferring the articles to a succeeding conveyor line.
There has been also another problem that it becomes difficult to remove the articles for sampling against the strong attractive force of the attractive magnet unit when it is desired to sample the articles in an inclined straight conveying area between the feed end and the terminal discharge end of the conveyor run, thus increasing a burden when sampling the articles within the inclined straight conveying area.